No reply yet from the OP after the number of other (even better) options postulated.
First of all, let me make it clear that the Sigma 70-300 is likely to disappoint as a macro lens. It loses contrast, colour rendition and sharpness (all to very high levels) once you get to the 200-300mm range and at the 'macro' focusing distances. It would be imprudent to want a macro lens and be advised to get it in favour of a dedicated macro lens.

But indeed if you want a longer focal length, then the 100mm varieties should serve your purposes much better than the 35 macro or 50mm options. You also have the Sigma 70mm macro, which is highly acclaimed, and the Tamron 90 macro which is perhaps the best bang for buck macro lens around.